To prevent a pressure-sensitive adhesive from firmly adhering to a substrate such as paper and plastic film, a surface of the substrate is coated with a silicone coating agent which is then cured to make a release layer on the substrate. A silicone pressure-sensitive adhesive mainly composed of an organopolysiloxane is widely used because a release layer thereof has good resistance to heat, coldness, and chemicals, good electric insulation and safety. The silicone pressure-sensitive adhesive has strong adhesion to a substrate, so that a silicone coating agent forming a good release layer should be used.
Such silicone coating agents are known, for example, a composition comprising an organopolysiloxane having a fluorine-containing substituent of the formula, CnF2n+1CH2CH2—, wherein n is an integer of 1 or larger, from Japanese Patent Publication of Examined Application No. 5-7434, and a composition comprising an organopolysiloxane having a fluorine-containing substituent of the formula, [CF(CF3)CF2O]nCF(CF3)CF2OCH2CH2CH2—, wherein n is an integer of from 1 to 5, from Japanese Patent Publication of Examined Application No. 4-76391. To apply these compositions, one has to dilute them with a diluent which preferably is a fluorinated solvent because of good solubility.
However, fluorinated solvents are expensive and have harmful effects on environment when they diffuse in the air. For these reasons, non-fluorinated solvents such as petroleum benzene, isooctane, hexane and diisopropyl ether are used as described in Japanese Patent Application Laid-Open No. 7-18185.